Certain types of printing systems are adapted for printing images on large-scale substrates, such as for example museum displays, billboards, sails, bus boards, and banners. Some of these systems use so-called drop on demand ink jet printing. In these systems, a carriage which holds a set of print heads scans or traverses across the width of the substrate while the print heads deposit ink as the substrate moves.
Solvent based inks are sometimes used in these systems to print on flexible substrates such as PVC materials and reinforced vinyl. However, water-based inks are typically considered to be more suitable for printing on textiles. In the past, print heads used for solvent based inks could not be used with water-based inks. More recently, print heads originally used with solvent-based inks have been modified to be compatible with water-based inks.
Unfortunately, by merely replacing solvent-based print heads in existing printer systems with modified print heads which are compatible with water-based inks, other difficulties have arisen. In particular, water-based inks have a tendency to mix with air as the inks flow though the ink transport system of the printers. That is, the water-based inks tend to aerate and become “foamy,” and hence degrade the printer capabilities of the printer.